I was looking over my eyepieces today from last night's observing and noticed that my BARCON convertible barlow now has a crack at the optic's edge. It's a new BARCON just used a few times and was carefully handled -- never dropped or bumped against anything. I'm wondering if I clamped it to tightly to my AP focuser last night. Could that focuser ring have added too much side pressure to the barrel around the optics? I'm just dumbfounded as to how this happened.

I had a very similar chip/crack appear in my BARCON several years ago after clamping down hard on the lens portion with a brass compression ring / set screw collar (AP collar).At the time my BARCON was at least a year old.I ended up buying another one and still have the cracked one.So far the 2nd BARCON hasn't chipped yet, but I now use Baader ClickLock collars instead.I think this was/is a flaw in the AP BARCON unit.Be careful about clamping these too tightly with set screws (even if you have a compression ring in your collar!

I was looking over my eyepieces today from last night's observing and noticed that my BARCON convertible barlow now has a crack at the optic's edge. It's a new BARCON just used a few times and was carefully handled -- never dropped or bumped against anything. I'm wondering if I clamped it to tightly to my AP focuser last night. Could that focuser ring have added too much side pressure to the barrel around the optics? I'm just dumbfounded as to how this happened.

The BARCON body is pretty solid and there is a little wiggle room for the glass, so I can't imagine clamping it hard enough to deform the body a couple mm to chip the glass. Not without using a wrench.

Is the chip in or outside of the light cone? If outside it is a nonissue.

Looking straight into the BARCON barrel from either end, I don't see the chip. The chip could still affect optical performance towards the center at this point. I'd like to call this a separation of two glass elements and it could grow towards the center as I continue using and clamping down the BARCON. Using the BARCON ahead of a Mark V bino with eyepieces is a bit of weight so the BARCON needs to be securely clamped down to hold properly. I had a small front window chip (5mm) in my SUV that has grown 100% over a year's time and will probably continue to grow.

I was looking over my eyepieces today from last night's observing and noticed that my BARCON convertible barlow now has a crack at the optic's edge. It's a new BARCON just used a few times and was carefully handled -- never dropped or bumped against anything. I'm wondering if I clamped it to tightly to my AP focuser last night. Could that focuser ring have added too much side pressure to the barrel around the optics? I'm just dumbfounded as to how this happened.

The BARCON body is pretty solid and there is a little wiggle room for the glass, so I can't imagine clamping it hard enough to deform the body a couple mm to chip the glass. Not without using a wrench.

Is the chip in or outside of the light cone? If outside it is a nonissue.

I can't really see how your BARCON is placed but here is what I do:
I place BARCON to Astro Physics adapter AP16T given additional light path added. This way, clamp pressure goes to AP16T adapter directly, not to BARCON.

I can't really see how your BARCON is placed but here is what I do:
I place BARCON to Astro Physics adapter AP16T given additional light path added. This way, clamp pressure goes to AP16T adapter directly, not to BARCON.

Tammy

That'll work. It also eliminates the gap that a few compression rings hang on.

Actually, I only used single eyepieces with the BARCON that night -- a couple of Delos and smaller TV Plossels. So, it wasn't even an issue with the heavier weight of a MkV + eyepieces.

Hi Peter,

I can't really see how your BARCON is placed but here is what I do:I place BARCON to Astro Physics adapter AP16T given additional light path added. This way, clamp pressure goes to AP16T adapter directly, not to BARCON.

Yes, I had my 1.25 dia. eyepieces (Delos and TV Plossels) in the AP 1.25 in. adapter and into the BARCON. The BARCON was inserted and clamped in the AP Maxbright diagonal that was in the AP 175EDF focuser. The BARCON was being held securely by the Maxbright diagonal. There is only one thumb screw on the Maxbright for accessories such as eyepieces and barlows. I don't see how this one thumb screw could squeeze the barrel of my BARCON to chip/crack/separate the lens inside. I've used this common configuration for many years with other Maxbright diagonals and BARCONs and this did not ever happen. I'm thinking that this most recent BARCON sample is flawed somehow.

Look at my photo: in the side-by-side view of the Delos/1.25" adapter/BARCON assembly and the Maxbright diagonal, the Maxbright's clamp ring (left side of Maxbright) doesn't even clamp around the BARCON barrel where the lens is in the BARCON. I clamps at least 1 in. up on the BARCON from where the lens is.

Hi Tammy,

Actually, I only used single eyepieces with the BARCON that night -- a couple of Delos and smaller TV Plossels. So, it wasn't even an issue with the heavier weight of a MkV + eyepieces.

Hi Peter,

You mean you just used BARCON like below?

If so, clamp pressure isn't on BARCON barrel but on 2" nosepiece above the BARCON unless 2" nosepiece does not go into focuser/diagonal deep enough to clear BARCON barrel?